Reply to "Compression too high?"

Many examples of modern high compression engines being built today & using octane rated fuel considerably lower than Doug's claimed 103 octane required fuel.

Here is just one example with the compression ratio being 11 to 1...

The 5.0 L (4948 cc, 302 cid)[10] "Coyote" V8 is the latest evolution of the Modular engine.[11] Ford engineers needed to design a V8, specifically for the Mustang GT, that would compete with the GM 6.2L LS3 used in the new Chevrolet Camaro, and the new Chrysler 6.4L Hemi ESF in the Charger, Challenger, and Grand Cherokee. This engine had to remain close to the same physical size of the outgoing 4.6, and share other specifications with it such as bore spacing, deck height, bell housing bolt pattern, etc. in order for the engine to utilize existing Modular production line tooling. The result was the 5.0 Coyote, which produced roughly the same amount of power as its competitors, but with a much smaller displacement. To strengthen the block enough to handle increased output, webbing was extensively used as reinforcement in the casting, rather than increasing the thickness of the walls. The intake plenum was also situated low between the two cylinder banks to meet the height constraint, thus the alternator traditionally placed low and center was moved to the side of the engine. It shares the 4.6 L's 100 mm (3.937 in) bore spacing and 227 mm (8.937 in) deck height,[12] while bore diameter and stroke have increased to 92.2mm (3.629 in) and 92.7mm (3.649 in), respectively. The engine also retains the 4.6 L's 150.7 mm (5.933 in) connecting rod length, which produces a 1.62:1 rod to stroke ratio.[13] The firing order has been changed from that shared by all previous Modular V8s (1-3-7-2-6-5-4-8) to that of the Ford Flathead V8 (1-5-4-8-6-3-7-2).[13] Compression ratio is 11.0:1, and despite having port fuel injection (as opposed to direct injection) the engine can still be run on 87 octane gasoline.

Another example with 10.9 to 1 compression ratio & requiring just 91 octane, 12 octane points lower than Doug's claimed as required 103 octane rating...

2013 Dodge Challenger SRT8 392
SPECIFICATIONS
All dimensions are in inches (millimeters) unless otherwise noted.
All dimensions are measured at curb weight with standard tires and wheels.
Note: Information shown is correct at time of publication, and is subject to change without notice.
GENERAL INFORMATION
Vehicle Type Two-door coupe
Assembly Plant Brampton, Ontario, Canada
EPA Vehicle Class Intermediate car
Introduction Date Summer 2012 as 2013 model
BODY
Layout Longitudinal front engine, rear-wheel drive
Construction Unitized steel body
ENGINE: 392 HEMI® V-8 (6.4 Liter)
Availability Standard
Type and Description 90-degree V-type, liquid-cooled
Displacement 392 cu. in. (6,417 cu. cm)
Bore x Stroke 4.09 x 3.72 (103.9 x 94.5)
Valve System Pushrod-operated overhead valves, 16 valves with sodium-filled exhaust
valves and hollow stem intake valves, 16 conventional hydraulic lifters, all
with roller tips
Fuel Injection Sequential, multi-port, electronic, returnless; automatic features Fuel
Saver mode
Construction Deep-skirt cast-iron block with cross-bolted main bearing caps, aluminum
alloy heads with hemispherical combustion chambers
Compression Ratio 10.9:1
Power (estimated SAE net) 470 bhp (351 kW) @ 6,000 rpm (73.4 bhp/liter)
Torque (estimated SAE net) 470 lb.-ft. (637 N•m) @ 4,200 rpm
Max. Engine Speed 6,400 rpm (electronically limited)
Fuel Requirement Premium 91 octane (R+M)/2 — recommended